Starter gearing for internal



Feb. 26, 1957 J. .1. SABATlNl 2,782,645

STARTER GEARING FOR INTERNAL. COMBUSTION ENGINES Filed July 5, 1955 a I "E- K W Z3 A i :9 5 7 16 I l 57440 *1 9 4i INVENTOR. dpfuv d (Sa ZY w A; BY j W 57034 K United States Patent STARTER GEARIN G FOR INTERNAL COMBUSTION ENGINES Application July 5, 1955, Serial No. 519,851 7 Claims. (Cl'. 74 --7) The present inventionre'lates to starter gearing for internal combustion engines and more particularly to that type in which connection of the starting motor to the engine is effected by acceleration of the starting motor, and disconnection is brought about by self-operation of the engine above a predetermined speed.

In devices of thistype where a pinion is traversed into engagement with an engine gear by means of a screwt-hreaded connection to the motor shaft, there is a substantial amount of kinetic energy stored in the rotating parts prior to completion of the meshing movement, and various forms of yielding driving connection are used to cushion the application of the deceleration torque developed by this kinetic energy when the engagement of the pinion is completed.

Cost considerations and space limitations have made the provision :of said yielding driving connections a major problem, andthe recent adoption of 12 -volt starting system for automotive engines involving high torque and very rapid acceleration of the motor have aggravated the problem.

Since the amount of kinetic energy stored in the rotating parts prior to full mesh of the pinion is a function of the amountoffree rotationo'f the startingmotor, it is desirable to reduce to apractical minimum the amount of rotation needed to mesh the inion. There is a limit to the pitch of the threaded connection, however, beyond which traversal of the pinion into initial mesh becomes uncertain.

It is an object of the present invention to provide a novel engine starter gear of the above type incorporating means for meshing the drive pinion with the engine gear responsive to a comparatively small arc of rotation of the starting motor.

It is another object to provide such a device in which the initial meshing movement of the pinion is brought about by a threaded connection, but the meshing movement is completed by an inclined connection of higher pitch than the threaded connection.

It is another object to provide such a device incorporating yielding means for normally holding the inclined connection in retracted position.

It is another object to provide such a device incorporating a yielding buffer for limiting the extension of the inclined connection.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation partly broken away and in section of a preferred embodiment of the invention showing the parts in normal or idle position;

Fig. 2 is a view similar to Fig. 1, showing the parts in the positions assumed when the pinion has started into mesh with the engine gear;

Fig. 3 is a View similar to Fig. 1 showing the parts in cranking position; and

Fig. 4 is a sectional detail taken substantially on the line 33 of Fig. 1.

2,782,645 Patented Feb. 23,1957v In Fig. 1' ofthe drawing there is illustrated apower shaft 1 on which a hollow sleeve 2- is fixedly mounted in any suitable manner as indicated'at 3. The sleeve 2 is formed with straight splines for a portion of its length as shown at 4, and a driving overrunning clutch member 5 is slid'ably and non-rotatably mounted thereon, being normally urged againsta lock ring 6 seated in a groove 7 in the sleeve by meansofa mesh-enforcing. spring 8 seated in acounter-bore of a thrust member 9 fixed in aiiy suitable manner on-the end of the sleeve 2.

A hollow screw shaft 11 is slidably j-ournalled on the sleeve 2 and is formed'on one end with overrunning clutch teeth 12 cooperating with similar teeth '13 on the clutch member 5. A stop member 14 is mounted on the other end of the sleeve 2, being maintained thereon by a lock ring 15 seated in a groove 16 inthe sleeve, and a spring Washer 17 located between the stop member 14 and the adjacent end ofthe screw'shaft 11 normally maintains the overrunning clutch teeth'12, 13 in engagement.

A pinion 18 is slida'bly' journalled on the power shaft 1 for movement into and out of mesh with a gear 19 on the engine to be started. Meansfor actuating the pinion from thescrew shaft l l'is provided comprising a control nut 21' threaded on the screw'shaft and a barrellmember indicated'generally by the numeral 22 for connecting the control nut to the pinion. Barrel member 22 is composed of two' parts 23 and 24" in order to facilitate assembly of thedr'ive, the two parts being anchored toge'ther by'means of'radial lugs 25 on the part 23 which engage in slots 2j6 in' the part 24,- and are retained-therein'bya lockrin'g' 27. The part 23 of the barrel is rigidly mounted'o'n the pinion 18' as indicated at 28,.and the part.24 of the barrel is provided with incline-d slots 29 formed to slidably receive'radial projections 31 of the control nut 21, the inclination of the connection 29, 31 being in thesa'me direction or hand, but substantially steeper than the pitch of the threads of the screw shaft 11.

Means is provided for normally maintaining the'projeetions 31 atthe right hand end of slots 29 asshown in Fig. 1, whereby the inclined connection is in' retracted position. This means is preferably in the form of a compression spring assh'own at 32, or may, if preferred, be in the form of a ring of elastically deformable material such as rubber, interposed between a terminal flange 33 on the barrel member 24 and a thrust washer 34- mounted on the control nut 21. A plurality of dished spring washers 35 are seated on the control nut between the projections 31 thereof and the thrust washer 34, said washers being maintained under initial compression by a lock ring 36 seated in a groove on the control nut.

The idle position of the control nut 21 on the screw shaft is defined by the ends 37 of the threads of the screw shaft. In order to prevent the control nut from drifting away from idle position, one or more of the threads on the screw shaft 11 are cut down to provide an inclined shoulder 40, and a spring pressed detent 38 (Fig. 4) is arranged to engage said shoulder to resist such drifting movement.

Means are provided for holding the pinion 18 in mesh with the engine gear 19 until the engine is operating at a predetermined speed. For this purpose a notch 39 is formed in the screw shaft to provide a shoulder 41 so positioned as to receive the detent 38 when the pinion is meshed with the engine gear and thereby prevent demeshing movement of the control nut until the detent is Withdrawn by centrifugal force.

In operation, starting with the parts in the positions as shown in Fig. 1, acceleration of the power shaft 1 by the starting motor, not illustrated, causes the screw shaft 11 to be rotated by the clutch member 5 whereby the control nut 21 is traversed in the meshing direction until its movement is arrested by the stop member 14, a thrust washer 42 being preferably interposed. At this time, the teeth of the pinion 18 have entered into initial meshing relation with the engine gear 19 as shown in Fig. 2. Further rotation of the power shaft causes the screw shaft 11 to be moved backward, compressing the mesh-enforcing spring 8 until the clutch member engages the thrust member 9 whereby its longitudinal movement is arrested. The torque transmitted from the screw shaft to the control nut then becomes operative to cause the inclined connection 29, 31 between the control nut and barrel member 24 to traverse the barrel and pinion assembly to the fully meshed position, compressing the spring 32 in the process as shown in Fig. 3. The final meshing movement of the pinion and barrel assembly brings the shoulder 43 of the barrel member 24 into engagement with the thrust washer 34, whereby the shock of engagement is cushioned by compression of the spring washers 35.

If, during the meshing movement, tooth abutment should occur between the pinion 18 and engine gear 19, the screw shaft and clutch member 5 are permitted by the mesh enforcing spring 8 to move backward and thereby provide time for torque to be built up to index the pinion teeth into proper registry with the tooth spaces of the engine gear.

It will be noted that since the traversing action of the screw shaft on the control nut is called upon only to secure initial engagement of the pinion with the engine gear, only a small amount of rotation of the power shaft 1 is needed, and since the completion of the meshing movement is brought about by the high pitch inclined connection 29, 31 between the control nut and barrel, the total rotation of the power shaft to secure meshing of the pinion is comparatively small and the kinetic energy stored up in the rotating parts is correspondingly reduced, thus minimizing the shock of engagement.

Although but one form of the invention has been shown and described in detail it will be understood that changes 7 may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an engine starter drive a power shaft, a sleeve fixed thereon, a screw shaft slidably journalled on the sleeve, means connecting the screw shaft to rotate with the sleeve, a pinion slidably journalled on the power shaft for movement into and out of mesh with a gear of the engine to be started, a control nut threaded on the screw shaft, means limiting the travel of the control nut on the screw shaft, means for actuating the pinion from the control nut including a barrel member fixed at one end to the pinion and having an inclined connection with the control nut of the same direction as the threads of the screw shaft but of steeper inclination, and yielding means for resisting meshing movement of the pinion and barrel with respect to the control nut.

2. An engine starter drive as set forth in claim 1 including further a yielding abutment limiting the meshing movement of the pinion and barrel with respect to the control nut.

3. An engine starter drive as set forth in claim 1 in which the meansfor connecting the screw shaft to rotate with the sleeve comprises a driving over-running clutch member splined on said sleeve, and yielding means urging said clutch member and screw shaft into clutching engagement.

4. An engine starter drive as set forth in claim 3 including further means for limiting the travel of the clutch member on the sleeve.

5. An engine starter drive as set forth in claim 3 in which the means for limiting the travel of the control nut on the screw shaft comprises a stop member on the sleeve, and the yielding means for urging the screw shaft and clutch member into engagement comprises a compression spring between said stop member and the screw shaft.

References Cited in the file of this patent UNITED STATES PATENTS Fitz Gerald May 21, 1940 Sekella Aug. 4, 1942 

